Remote Water Quality Monitoring System using Solar-Powered and Long-Range Communication

Abstract

This paper presents an energy-autonomous water-quality monitoring system for remote sites that couples a solar-harvested ESP32-LoRa node with pH, turbidity, total dissolved solids (TDS), and temperature sensing, and a receiver-to-web relay for real-time visualization. The node is powered via MPPT-regulated photovoltaics and a LiFePO₄ buffer battery, enabling continuous operation without grid access. Sensors were calibrated against reference instruments (NIST-traceable buffers for pH, diluted formazin standards for turbidity, and NaCl conductivity standards for TDS) and evaluated on laboratory water samples. Across all parameters, sensor readings closely tracked references, with percentage differences within single-digit ranges and <0.5% for temperature. The asynchronous web server reliably displayed live measurements, demonstrating end-to-end data availability. Compared with recent LoRa/LoRaWAN deployments, the design emphasizes solar autonomy and a lightweight server pipeline for intermittent connectivity. The approach offers a practical pathway to low-cost, long-range monitoring that can be adapted to rural and peri-urban environments.